Worcester Highflow 4.5 boiler

[Rockhopper]

My Worcester Highflow 4.5 boiler is acting up and I wonder if anyone can
advise me. Today the hot water is working but the heating has gone off, the pilot light is still lit, and the boiler kicks in fine for heating the hot water. I've checked a couple of my radiators and they don't have any air in them. When I put my fingers on the heating pump it is faintly vibrating, also the pipe on the outflow end of the pump is hot along with the heating return pipe. Which components could be causing the
fault? How can I check they are / are not working?
In advance
Thanks
Dave

 

[croydoncorgi]

Diverter stuck? Maybe room thermostat not calling for heat?
(If the boiler is firing for hot water and the pump's running when there's NO call for hot water and the internal heatstore has had time to recover, it's got to be the diverter.

 

[Rockhopper]

Diverter stuck? Maybe room thermostat not calling for heat?
(If the boiler is firing for hot water and the pump's running when there's NO call for hot water and the internal heatstore has had time to recover, it's got to be the diverter.

Thanks for your response.
No room thermostats fitted only rad valve stats, How can I check if the diverter is stuck?

 

[croydoncorgi]

From the Highflow 400 diagnostic guide:

Central heating watercold or luke warm during CH demand.

Suspect: Water diverter valve not closing. Disconnect the two pole plug from the diverter valve coil and run the boiler in CH mode. Measure the
voltage across the two connections within the plug, Is there 25 35 Vdc?

(If NO - PCB problem)

If YES, Measure the resistance of the diverter valve coil. Is it 150 250 ohms

If NO, replace coil, If YES, replace diverter valve.

Note: replacing the valve is NOT straightforward! (2 pages of text in manual).

 

[Rockhopper]

From the Highflow 400 diagnostic guide:

Central heating watercold or luke warm during CH demand.

Suspect: Water diverter valve not closing. Disconnect the two pole plug from the diverter valve coil and run the boiler in CH mode. Measure the
voltage across the two connections within the plug, Is there 25 35 Vdc?

(If NO - PCB problem)

If YES, Measure the resistance of the diverter valve coil. Is it 150 250 ohms

If NO, replace coil, If YES, replace diverter valve.

****!! It seems I am in deep doo doo

 

[redboris]

I have exactly the same symptoms and set up. Did you get this resolved? What was the problem in the end?
Thanks

 

[superdupergasman]

diverter valves on a 400 are alot easier to change than alot of boilers out there! the manf inst take you through it step by step!